There are numerous objects in space. Among these space objects are asteroids, meteors, planets, stars and even debris (also known as space junk). An asteroid is a large, irregularly shaped object in space that orbits our Sun. An asteroid is like a comet, however, while comets are mostly made of ice, asteroids are made up of rock or metal. This makes asteroids more dangerous than other space objects because they can cause a lot of damage if they collide with a planet. The craters on the Moon were formed by asteroids and a popular theory suggests that it was an asteroid that wiped out the dinosaurs. Around a million asteroids are located between Mars and Jupiter in an area called the “asteroid belt.”
There are an unknown number of asteroids in varying sizes and orbits, and only about 1,000 are actively tracked. We know on a frequent basis a new asteroid is identified with projected paths near Earth and impact times is in days. The asteroid which impacted Jupiter on 19 Jul. 2009 caused damage thought to be equivalent in size to the Pacific Ocean, but it was not detected before the impact. Many small asteroids impact Earth on a daily basis and a few cause considerable damage every decade. Others are of such a size that their impact could end life on Earth as we know it, such as the one that ended the dinosaurs. The first observation of asteroids can be when impact actually occurs as happened recently in Russia.